The present invention is directed to an optical system. Specifically, the invention is directed to a housing for optical equipment used to survey the conditions in a hostile environment.
Hostile environments exhibit conditions that are detrimental to optical systems and their related housings. High temperatures, debris and smoke can quickly damage sensitive optical components. Despite these conditions, operators need to observe conditions inside the hostile environment. Several conventional optical systems exist for surveying hostile environments.
U.S. Pat. No. 3,021,385 to Summerhayes, Jr. et al. describes a flame observation system insertable into the wall of a combustion chamber. A housing stores a lens and a camera. The housing has a small aperture near the lens. Compressed air is provided to the housing. The air escapes through the aperture, both cooling the lens and preventing particles and smoke from contaminating the lens.
U.S. Pat. No. 5,139,412 to Kychakoff et al. describes an apparatus for profiling the bed of a furnace. A camera mounts to a proximal end of the lens tube assembly. The lens tube assembly is inserted into an air port of the furnace. Compressed air is provided to the tube assembly for cooling the lenses and sweeping debris from the open distal end of the tube assembly.
U.S. Pat. No. 5,155,358 to Larson describes a double wall housing for a camera used to survey a boiler. A baffle assembly is provided between the inner and outer walls. A thermoswitch operates at a given temperature to supply compressed air to the space between the inner and outer wall for cooling.
U.S. Pat. No. 5,162,906 to Yorita et al. describes an apparatus for observing the interior of a hot furnace. The camera case is jacketed for water cooling. Compressed air is supplied to the interior of the camera case for cooling. The air exits through a slit near the several glass plates. The glass plates allow selective wave-lengths to pass therethrough for viewing by the video camera.
U.S. Pat. No. 5,485,237 to Adermann et al. describes a protective camera housing and optical system used during blasting operations in underground mines. The case has a blast-proof inner and outer frame. The casing is inserted into the wall of a mine shaft. A small portion of the casing, housing the optical prism, projects into the mine shaft. The optical prism allows the camera to "look around corners" during blasting.
U.S. Pat. No. 5,592,217 to Hirvonen et al. describes an assembly for monitoring a combustion chamber. The support tube includes a hole at a distal end used as an aperture stop. The support tube also has an outer thermal shield, with a channel therebetween. Cooling air is provided to the support tube and the channel. The air exits through the hole at the distal end, preventing contaminants from damaging the lenses.
Hostile environments are not designed with an eye towards allowing effortless viewing of the contents therein. The placement of viewing ports in furnaces, ovens, etc. has a low design priority, often as an afterthought. The viewing ports must also be small in order to avoid heat loss from the hostile environment. For example, a viewing port could have an opening as small as approximately 2" in diameter. The viewing assembly must be able to operate within these limited spatial dimensions.
In addition, the viewing assembly must also be capable of deep insertion within the hostile environment. The desired viewing location within the hostile environment may not be adjacent the viewing port. This requires the observation equipment to traverse a distance within the hostile environment, subjecting the viewing assembly to even higher temperatures. Conventional assemblies do not exhibit any of these capabilities.
Furthermore, all of the conventional assemblies described herein require air and/or water cooling systems to prevent damage to the optical components. All of the conventional assemblies only provide one image of the hostile environment. The conventional assemblies that use a double wall arrangement provide for fluid movement between the inner and outer walls.
Clearly, there is room for improvement in the art.